Method for hydrophobing leather and furskins

ABSTRACT

Water repellency is imparted to leather and fur skins by a process in which leather or fur skin is treated, before, during or after the retanning, with one or more formulations comprising from 1 to 30% by weight, based on the formulation, of a mixture of polysiloxanes comprising from 10 to 90% by weight, based on the mixture, of one or more carboxyl-containing polysiloxanes, from 90 to 10% by weight, based on the mixture, of one or more carboxyl-free polysiloxanes and from 3 to 25% by weight, based on the formulation, of at least one emulsifier.

The present invention relates to a process for imparting waterrepellency to leather and fur skins, wherein leather or fur skin istreated, before, during or after the retanning, with one or moreformulations comprising from 1 to 30% by weight, based on theformulation, of a mixture of polysiloxanes comprising

from 10 to 90% by weight, based on the mixture, of one or morecarboxyl-containing polysiloxanes,

from 90 to 10% by weight, based on the mixture, of one or morecarboxyl-free polysiloxanes

and from 3 to 25% by weight, based on the formulation, of at least oneemulsifier.

EP 0 213 480 B discloses a process for imparting water repellency toleather and fur skins, in which an aqueous emulsion of a silicone oil oran anhydrous mixture of a silicone oil and an alkanolamine salt of anamino acid is allowed to act on leather or skins before, during or afterthe retanning. Examples of polysiloxanes are: dimethylpolysiloxane inwhich 3% of the methyl groups have been replaced by mercaptopropyl(examples 1 to 7), dimethylpolysiloxane having a viscosity from 80 to110 mPa·s, phenylmethylpolysiloxanes having a viscosity from 85 to 120mPa·s and dimethylpolysiloxanes having on average from 2 to 10 carboxylgroups per molecule. The performance characteristics of such waterrepellent formulations can however still be improved. Furthermore, theleathers produced with the aid of the polysiloxanes disclosed can insome cases also be improved with regard to performance characteristics.

WO 95/22627 discloses a process for imparting water repellency toleather and fur skins using carboxyl-containing polysiloxanes in aqueousemulsion, in which polysiloxanes which are branched in a comb-likemanner and may have the formula A are used:

The structural units may, for example, be randomly distributed. Thevariables are defined as follows:R are identical or different and, independently of one another, arehydrogen, hydroxyl, C₁-C₄-alkyl, phenyl, C₁-C₄-alkoxy, amino, mono- ordi-C₁-C₄-amino, chlorine or fluorine, it also being possible in eachcase for a radical R to be the group Z-A-COOH at the chain ends;A is a linear or branched C₅-C₂₅-alkylene group andZ is a direct bond, an oxygen atom or an amino, carbonyl, amido or estergroup.

On average, preferably from 2.5 to 15 carboxyl groups are present permolecule (page 4, line 17).

Leather and fur skin treated with the aid of such comb-likepolysiloxanes generally have very good water repellency.

WO 98/04748 discloses a process for retanning leathers produced usingpolymeric tanning agents and, if required, aldehyde tanning agents,which leathers are treated with polymer tanning agents and withcomb-like polysiloxanes of the formula A defined above.

EP-A 1 087 021 discloses that leather treatment compositions comprisinga combination of polysiloxanes substituted by carboxyl or carboxylicanhydride groups at the α,ω-position, the carboxyl groups of thepolysiloxane being present in neutralized form, with certain amphiphilicpolymers, an emulsifier and an oil or wax are suitable as leathertreatment compositions. With the aid of the combination productsdisclosed, full and soft leathers which were readily washable wereproduced.

However, it is observed that leather and fur skin obtained according tothe publications cited above have in many cases a dyeing with anundesirably low degree of levelness. Moreover, the high price of thepolysiloxanes branched in a comb-like manner is to be regarded asdisadvantageous.

It is an object of the present invention to provide a process for theproduction of leather and fur skins which does not have theabovementioned disadvantages. It is further-more an object of thepresent invention to provide leather having advantageous performancecharacteristics.

It is moreover an object of the present invention to provide novelformulations having advantageous performance characteristics.

We have found that this object is achieved by the process defined at theoutset. According to the invention, leather is treated with aformulation before, during or after the retanning.

At least one formulation used in the novel process comprises from 1 to30, preferably from 5 to 20, particularly preferably from 7 to 12.5, %by weight, based on the weight of the formulation, of a mixture of twoor more polysiloxanes.

From 10 to 90% by weight, based on the mixture, of the polysiloxanescomprised in at least one formulation are carboxyl-containingpolysiloxanes.

In an embodiment, carboxyl-containing polysiloxanes are those whichcontain the structural elements of the formulae I and II and optionallystructural elements III a and/or III b.

The structural elements defined above are each arranged in such a waythat Si—O—Si—O chains are formed. Formation of Si—Si groups istheoretically possible but plays a minor role in most cases.

In the formulae I, II, III a and III b, the variables are defined asfollows:

R¹ are identical or different and, independently of one another, arehydrogen,

hydroxyl,

C₁-C₄-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl and tert-butyl; in particular methyl;

C₆-C₁₄-aryl, for example phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl,2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl,4-phenanthryl and 9-phenanthryl, preferably phenyl, 1-naphthyl and2-naphthyl, particularly preferably phenyl;

C₁-C₄-alkoxy, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy,isobutoxy, sec-butoxy and tert-butoxy;

amino,

mono-C₁-C₄-alkylamino, for example —NHCH₃, —NHC₂H₅, —NH(CH₂)₂CH₃,—NH(CH₂)₃CH₃, —NH—CH(CH₃)₂, NHC(CH₃)₃;

di-C₁-C₄-alkylamino, —N(CH₃)₂, —N(C₂H₅)₂, —N(CH₃)(C₂H₅), —N[(CH₂)₂CH₃]₂,—N(CH₃)CH(CH₃)₂,

or Z¹-A¹—COOH.

In a preferred embodiment of the present invention, all R¹ are identicaland are each methyl.

In another preferred embodiment, the structural elements I are identicalin each case, in I in each case one R¹ being methyl and the other R¹being phenyl.

In an embodiment of the present invention, the structural elements ofthe formula III a are selected from the following groups: Si(CH₃)₃,Si(CH₃)₂C₆H₅, Si(CH₃)₂OH, Si(CH₃)C₆H₅OH.

A¹ are identical or different and are linear or branchedC₅-C₂₅-alkylene, unsubstituted or substituted by one or more C₁-C₄-alkylor phenyl, for example

—(CH₂)₅—, —(CH₂)₆—, —(CH₂)₈, —(CH₂)₈—, —(CH₂)₉—, —(CH₂)₁₀—, —(CH₂)₁₁—,—(CH₂)₁₂—, —(CH₂)₁₃—, —(CH₂)₁₄—, —CH(CH₃)—CH₂—CH₂—CH₂—CH(CH₃)—,—C(CH₃)₂—CH₂—CH₂—CH₂—CH(CH₃)—;

—CH(C₆H₅)—CH₂—CH₂—CH₂—CH(CH₃)—; preferably —(CH₂)₈—, —(CH₂)₉—,—(CH₂)₁₀—, —(CH₂)₁₁—, —(CH₂)₁₂—;

it being possible for C₅-C₂₅-alkylene to be interrupted by 1 to 8 oxygenatoms not directly bonded to one another.

Z¹ is

a direct bond,

oxygen

an amino group of the formula —NR²

a carbonyl group,

an amido group of the formula —NR²—CO— or —CO—NR²— or

an ester group of the formula CO—O or O—CO;

R² are identical or different and, independently of one another, areselected from hydrogen,

C₁-C₄-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl and tert-butyl.

Polysiloxanes which comprise the structural elements of the formulae I,II and optionally III a and/or III b may be linear or have a cyclic orbranched structure. Branched polysiloxanes which comprise the structuralelements I, II and optionally III a and/or III b generally additionallycomprise structural elements, for example of the formula IV a or IV b

in which the variables are defined as above. Cyclic straight-chainpolysiloxanes which comprise the structural elements of the formula I orII usually comprise no structural elements of the formulae III a and IIIb.

The structural elements I, II and optionally IV a and IV b can bedistributed alternately, blockwise and preferably randomly incarboxyl-containing polysiloxane molecules.

In an embodiment of the present invention, carboxyl-comprisingpolysiloxanes contain from 1 to 50, preferably from 2 to 25,particularly preferably from 2.5 to 15, carboxyl groups per molecule.

Usually, the molecular weight M_(w) of the carboxyl-containingpolysiloxanes used according to the invention and having the structuralelements I, II, optionally III a, III b, IV a and IV b is from 5 000 to150 000, preferably from 10 000 to 100 000, g/mol.

The molecular weight determination can be carried out by methods knownto a person skilled in the art, for example by light scattering methodsor viscosity determinations.

In an embodiment of the present invention, all or at least a certainproportion, for example a third or a half, of the carboxyl groups in thecarboxyl-containing poly-siloxanes are neutralized. For example, basicsalts, such as hydroxides or carbonates of the alkali metals, forexample Na or K, are suitable for the neutralization. Ammonia,alkylamines, such as methylamine, dimethylamine, trimethylamine,ethylamine, diethylamine, triethylamine and ethylenediamine, andalkanolamines, such as ethanolamine, diethanolamine, triethanolamine,N-methylethanolamine, N-methyl-diethanolamine orN-(n-butyl)diethanolamine, are furthermore suitable.

The mixtures used according to the invention comprise, for example, from10 to 90, preferably from 40 to 60, particularly preferably about 50, %by weight, of carboxyl-containing polysiloxane.

The mixtures used according to the invention furthermore comprisepolysiloxanes which comprise no carboxyl groups. Such polysiloxanesgenerally comprise structural units of the above-defined formulae I,optionally III a, III b and IV a, the variables being defined as above,but R¹ is not Z¹-A¹—COOH. Carboxyl-free polysiloxanes used according tothe invention are preferably composed of structural elements of theabove-defined formulae I, optionally III a, III b and IV a.

Particularly preferably used carboxyl-free polysiloxanes arepoly(dimethyl)siloxanes and poly(phenylmethyl)siloxanes.

Carboxyl-free polysiloxanes which comprise the structural elements ofthe formulae I and optionally III a, III b and IV a may have a linear orcyclic or branched structure. Branched carboxyl-free polysiloxanes whichcomprise the structural elements I and optionally III a and/or III bgenerally additionally comprise structural elements, for example of theformula IV a. Cyclic straight-chain carboxyl-free polysiloxanes whichcomprise the structural elements of the formula I usually comprise nostructural elements of the formulae III a and III b.

In a preferred embodiment of the present invention, all R¹ incarboxyl-free polysiloxanes are identical and are each methyl.

In another preferred embodiment, the structural elements I incarboxyl-free polysiloxanes are in each case identical, in I in eachcase one R¹ being methyl and the other R¹ being phenyl.

In an embodiment of the present invention, the structural elements ofthe formula III a in carboxyl-free polysiloxanes are selected from thefollowing groups: Si(CH₃)₃, Si(CH₃)₂C₆H₅, Si(CH₃)₂OH, Si(CH₃)C₆H₅OH.

Usually, the molecular weight M_(w) of the carboxyl-free polysiloxanesused according to the invention and having the structural elements I,II, optionally III a, III b and IV a is from 500 to 150 000, preferablyup to 10 000, g/mol.

In a preferred embodiment of the present invention, carboxyl-containingand carboxyl-free polysiloxanes are chosen so that the molecular weightof the carboxyl-containing polysiloxane is higher than the molecularweight of the carboxyl-free polysiloxane.

The mixtures used according to the invention comprise, for example, from10 to 90, preferably from 40 to 60, particularly preferably about 50, %by weight of carboxyl-free polysiloxane.

The formulations used according to the invention comprise one or moreemulsifiers. For example, from 3 to 25, preferably from 5 to 20,particularly preferably from 8 to 18, % by weight, based on theformulation, of one or more emulsifiers are.

In principle, all compounds which are surface-active in aqueous systemsand may be nonionic, anionic, cationic or zwitterionic can be used asemulsifiers.

Particularly suitable emulsifiers are N-acylated amino acid derivatives,for example of the formula V

in which the variables are defined as follows:

-   R³ is hydrogen,    -   C₁-C₄-alkyl, such as methyl, ethyl, n-propyl, isopropyl,        n-butyl, isobutyl, sec-butyl and tert-butyl, in particular        methyl;    -   C₆-C₁₄-aryl, for example phenyl, 1-naphthyl, 2-naphthyl,        1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl,        3-phenanthryl, 4-phenanthryl and 9-phenanthryl, preferably        phenyl, 1-naphthyl and 2-naphthyl, particularly preferably        phenyl;-   R⁴ is C₁-C₄-alkyl, such as methyl, ethyl, n-propyl, isopropyl,    n-butyl, isobutyl, sec-butyl and tert-butyl; in particular methyl;

The group CO—R⁵ is usually derived from saturated or unsaturated fattyacids. Saturated fatty acids are to be understood as meaning carboxylicacids which have C₉-C₂₀-alkyl and may be linear or branched, substitutedor unsubstituted. R⁵ may be, for example, n-nonyl, n-decyl, n-dodecyl,n-tetradecyl, n-pentadecyl, n-octadecyl or n-eicosyl.

CO—R⁵ may be derived from an unsaturated fatty acid of 9 to 20 carbonatoms and one having up to 5° C.—C double bonds, it being possible forthe C—C double bonds to be, for example, isolated or allylic, forexample the acyl radical of linoleic acid, of linolenic acid and veryparticularly preferably of oleic acid.

In an embodiment of the present invention, all or at least a certainproportion, for example a third or a half, of the carboxyl groups areneutralized in N-acylated amino acid derivatives used as emulsifiers.For example, basic salts such as hydroxides or carbonates of the alkalimetals, for example, Na or K, are suitable for neutralization. Ammonia,alkylamines, such as methylamine, dimethylamine, trimethylamine,ethyl-amine, diethylamine, triethylamine and ethylenediamine, andparticularly preferably alkanolamines, such as ethanolamine,diethanolamine, triethanolamine, N-methyl-ethanolamine,N-methyldiethanolamine or N-(n-butyl)diethanolamine, are furthermoresuitable for the neutralization.

Typical examples of compounds of the formula V are N-oleylsarcosine,N-stearyl-sarcosine, N-lauroylsarcosine and N-isononanoylsarcosine andthe respective ethanolammonium salts, diethanolammonium salts andN-methyldiethanolammonium salts.

In an embodiment of the present invention, sulfur-containing emulsifieris used.

Sulfur-containing emulsifiers which may be used are in principle allsulfur-containing compounds which are surface-active in aqueous systemsand may be nonionic, anionic, cationic or zwitterionic.

Particularly suitable compounds are those of the formula VI

in which the variables are defined as follows:

-   R⁶ and R⁷ are identical or preferably different and are selected    from hydrogen,    -   C₁-C₃₀-alkyl, branched or straight-chain, such as methyl, ethyl,        n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl,        n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl,        isoamyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl,        n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl,        n-tetra-decyl, n-hexadecyl, n-octadecyl and n-eicosyl,        preferably β-branched radicals of the formula VI a    -   (CH₂CH₂O)_(x)—O—R or [CH(CH₃)CH₂O)_(x)—O—R, where x is an        integer in the range from 1 to 20,    -   C₆-C₁₄-aryl, for example phenyl, 1-naphthyl, 2-naphthyl,        1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl,        3-phenanthryl, 4-phenanthryl and 9-phenanthryl, preferably        phenyl, 1-naphthyl and 2-naphthyl, particularly preferably        phenyl;-   R⁸ is selected from C₁-C₄-alkyl, such as methyl, ethyl, n-propyl,    isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl    -   and in particular hydrogen;-   R⁹ and R¹⁰ are identical or preferably different and are selected    from C₁-C₂₇-alkyl, such as methyl, ethyl, n-propyl, isopropyl,    n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,    sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl,    isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl,    n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl,    n-octadecyl, n-eicosyl;    -   the sum of the carbon atoms of R⁹ and R¹⁰ being not more than        30.    -   R⁹ preferably has two carbon atoms more than R¹⁰; for example,        the combinations    -   R⁹=n-undecyl and R¹⁰=n-nonyl,    -   R⁹=n-dodecyl and R¹⁰=n-decyl,    -   R⁹=n-tridecyl and R¹⁰=n-undecyl,    -   R⁹=n-tetradecyl and R¹⁰=n-dodecyl,    -   R⁹=n-pentadecyl and R¹⁰=n-tridecyl,    -   are preferred,-   R¹¹ is selected from C₁-C₄-alkyl such as methyl, ethyl, n-propyl,    isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl,    -   phenyl, ortho-tolyl, meta-tolyl and para-tolyl    -   and in particular hydrogen.

In a preferred embodiment of the present invention, exactly one of theradicals R⁶ and R⁷ is hydrogen and the other radical is selected fromC₁-C₃₀-alkyl.

In a particularly preferred embodiment of the present invention, amixture of a plurality of sulfur-containing compounds is chosen, forexample of the formula VI, which may differ, for example, in that, inthe first compound of the formula VI, R⁶ is hydrogen and R⁷ is selectedfrom C₁-C₃₀-alkyl and, in the second one, R⁶ is hydrogen and R⁷ isselected from C₁-C₃₀-alkyl.

In an embodiment of the present invention, all or at least a certainproportion, for example a third or a half, of the sulfonyl groups insulfur-containing compounds used as emulsifiers are neutralized. Forexample, basic salts, such as hydroxides or carbonates, of the alkalimetals, such as, for example, Na or K, are suitable for theneutralization. Ammonia, alkylamines, such as, for example, methylamine,dimethyl-amine, trimethylamine, ethylamine, diethylamine, triethylamineor ethylenediamine, and very particularly alkanolamines, such as, forexample, ethanolamine, diethanolamine, triethanolamine,N-methylethanolamine, N-methyldiethanolamine orN-(n-butyl)-diethanolamine, are furthermore suitable for theneutralization.

The preparation of compounds of the formula VI is known per se and isdescribed in WO 01/68584. It is effected, for example, by mono- ordiesterification of dicarboxylic anhydrides of the general formula VII

with corresponding alcohols, which need not be present in pure form,followed by a reaction with disulfite.

Instead of pure sulfur-containing compounds, for examplesulfur-containing compounds of the formula V, it is possible to usemixtures of different sulfur-containing compounds. For example, it ispossible to use, for the esterification, the mixture known as oxo oil135 or oxo thick oil 135 (WO 01/68584).

In an embodiment of the present invention, formulations used in theprocess according to the invention may comprise up to 40% by weight,preferably up to 20% by weight, based on the formulation, of at leastone alcohol of the formula VIII

where, in formula VIII, the variables R⁹ and R¹⁰ are defined as above.

In an embodiment of the present invention, formulations used in theprocess according to the invention may comprise up to 50% by weight,preferably up to 30% by weight, based on the formulation, of at leastone compound of the formula VIII.

In a preferred embodiment of the present invention, formulations used inthe process according to the invention may comprise up to 40% by weight,particularly preferably up to 20% by weight, of mixtures which compriseat least one alcohol of the general formula VIII; oxo oil 135 and oxooil 13 may be mentioned by way of example of such mixtures.

The formulation or the formulations used according to the invention isor are preferably aqueous.

In an embodiment of the present invention, at least one formulation usedaccording to the invention comprises at least one further hydrophobiccompound. At least one further hydrophobic compound is a carbon-basedcompound, for example natural or synthetic wax, natural or synthetic oilor natural or synthetic fat.

Examples of natural waxes are beeswax, cork wax, montan waxes andCarnauba wax.

Examples of synthetic waxes are polyethylene waxes or ethylene copolymerwaxes, as obtainable, for example, by free radical polymerization ofethylene or free radical copolymerization of ethylene with, for example,(meth)acrylic acid or by Ziegler-Natta catalysis. Polyisobutylene waxesmay furthermore be mentioned. Paraffin mixtures may also be mentioned;these are to be understood as meaning mixtures of hydrocarbons whichhave 12 or more carbon atoms and usually have a melting point of from 25to 45° C. Such paraffin mixtures can be obtained, for example, inrefineries or crackers and are known to a person skilled in the art asparaffin slack wax and sasol waxes. Montan ester waxes are a furtherexample of synthetic waxes.

Examples of natural oils are triglycerides which are liquid at roomtemperature, for example fish oil, neatsfoot oil, olive oil, cotton seedoil, castor oil, sunflower oil and peanut oil.

Examples of synthetic oils are white oil, liquid paraffin,functionalized paraffins, such as chlorinated or sulfochlorinatedparaffins, and polyalkylene glycols, such as polyethylene glycol.

Examples of natural fats are natural triglycerides which are solid atroom temperature, such as lanolin, shellac wax and mixtures thereof.

In a preferred embodiment of the present invention, the furtherhydrophobic compound is at least one natural triglyceride.

In a further preferred embodiment, a combination of at least one naturaltriglyceride which is solid or liquid at room temperature and a paraffinmixture having a melting point of from 25 to 40° C. is used. The ratiois not critical per se, and weight ratios of natural triglyceride toparaffin mixture of from 10:1 to 1:10 are suitable.

According to the invention, from about 10 to 70, preferably from 20 to40, % by weight, based on the formulation, of one or more furtherhydrophobic compounds can be used.

For carrying out the novel process, leather or fur skin is treated in aliquor, before, during or after the retanning, with the formulationsused according to the invention. The novel treatment can be carried outonce or repeatedly. The leathers to be treated may have been produced byany desired method, for example by mineral tanning, in particular chrometanning, or by polymer tanning, tanning with syntans, resin tanning,tanning with vegetable tanning agents or tanning with combinations ofthe abovementioned tanning agents.

In an embodiment of the novel process, at least one novel formulation isadded in one or more portions to the leather to be treated or to theskins to be treated. This addition can be effected in an aqueous liquor.Preferably, the liquor length may be from 50 to 2 000, preferably from100 to 400, % by weight, based on the shaved weight of the leathers orthe wet weight of the fur skin.

In an embodiment of the novel process, the componentscarboxyl-containing polysiloxane, carboxyl-free polysiloxane andemulsifier are added separately to the leather and/or leather and liquorand the novel formulation is prepared in situ.

The novel process is carried out in general by drumming the leather tobe treated or the fur skin to be treated in suitable vessels, forexample in barrels, in particular in rotatable barrels having internals.Other methods known to a person skilled in the art are also possible forthorough mixing.

Temperatures of from 20 to 65° C., preferably from 30 to 60° C., can bechosen as the temperature for the novel process.

The pressure conditions of the novel process are in general notcritical. Atmospheric pressure (1 atm) is preferably employed, but it isalso possible to employ reduced pressure, for example from 0.5 to 0.99atm, or superatmospheric pressure, for example from 1.01 to 2 atm.

A pH of from 4 to 8, preferably from 4.5 to 8, can be established as thepH at the beginning of the novel treatment. At the end of the noveltreatment, the pH can be reduced by adding an acid, for example formicacid, to a pH of from 3 to 5.

The novel treatment is generally complete after a time of from 20minutes to 24 hours, preferably from 30 minutes to 12 hours. If thetreatment is carried out repeatedly, the term novel treatment steps isused in the context of the present invention.

The amount of the formulation used according to the invention may befrom 0.1 to 20, in particular from 0.5 to 15, % by weight, based on theshaved weight of the leathers to be treated or the wet weight of theskins to be treated.

During the novel treatment, conventional leather dyes can be added tothe liquor. Suitable examples are acidic, substantive or basic anilinedyes, which can be used in amounts customary in tanning.

If it is desired to carry out the novel treatment during the retanning,any desired tanning agents customary in the tannery can, for examplemineral tanning agents, in particular chrome tanning agents, or polymertanning agents, syntans, resin tanning agents, vegetable tanning agentsor combinations of the abovementioned tanning agents.

During the novel treatment, organic solvents, for example alcohols, canbe added. However, the procedure is preferably carried out withoutaddition of organic solvents.

The novel treatment can be supplemented by an aftertreatment withtanning agents customary in the tannery, for example mineral tanningagents, in particular chrome tanning agents, or with polymer tanningagents, syntans, resin tanning agents, vegetable tanning agents orcombinations of the abovementioned tanning agents.

After the novel treatment, the leathers obtained or fur skins obtainedaccording to the invention can be worked up in the manner customary intanning.

The present invention furthermore relates to leathers produced by thenovel process. Said leathers have very good performance characteristics,for example very good water repellency, very good handle andoutstandingly level dyeing.

The present invention furthermore relates to the use of the novelleathers for the production of articles of clothing, for examplejackets, coats, shoes and in particular boots. The present inventionfurthermore relates to the use of the novel leather for the productionof pieces of furniture and furniture parts, for example leather sofas,leather armchairs, arm rests for chairs, arm chairs or sofas or benches.The present invention furthermore relates to the use of the novelleathers for the production of automotive parts, for example automobileseats, parts of dashboards and interior trim parts, for example in cardoors.

The present invention furthermore relates to fur skins treated by thenovel process.

The present invention furthermore relates to formulations comprising

from 1 to 20% by weight, based on the formulation, of a mixture ofpolysiloxanes, comprising

from 10 to 90% by weight, based on the mixture, of one or morecarboxyl-containing polysiloxanes,

from 90 to 10% by weight, based on the mixture, of one or morecarboxyl-free polysiloxanes,

and from 3 to 25, preferably from 5 to 20, particularly preferably from8 to 18, % by weight, based on the formulation, of at least oneemulsifier.

In an embodiment of the present invention, the novel formulations areformulations wherein the carboxyl-containing polysiloxanes are thosepolysiloxanes which comprise the structural elements of the formulae I,II and optionally III a and III b.

The structural elements of the formulae I, II, III a and III b aredefined as above.

The carboxyl-containing polysiloxanes comprised in the novelformulations may furthermore comprise structural elements of theformulae IV a and IV b.

In an embodiment of the present invention, the carboxyl-freepolysiloxanes comprised in the novel formulations are thosepolysiloxanes which generally comprise structural elements of theabove-defined formulae I and optionally III a, III b and IV a, thevariables being defined as above. Preferred carboxyl-free polysiloxanescomprised in the novel formulation are composed of structural elementsof the above-defined formulae I comprise and optionally III a, III band/or IV a.

In principle, all compounds which are surface-active in aqueous systemsand may be nonionic, anionic, cationic or zwitterionic may be mentionedas emulsifiers in the novel formulations.

Particularly suitable emulsifiers are N-acylated amino acid derivatives,for example of the formula V, in which the variables are defined asabove.

Other suitable emulsifiers are sulfur-containing emulsifiers.

In principle, all sulfur-containing compounds which are surface-activein aqueous systems and may be nonionic, anionic, cationic orzwitterionic may be mentioned as sulfur-containing emulsifiers in theformulations according to the invention.

Particularly suitable emulsifiers are sulfur-containing compounds, forexample of the formula VI, in which the variables are defined as above.

In an embodiment of the present invention, the novel formulations arethose formulations which comprise from 10 to 70% by weight, based on theformulation, of at least one further hydrophobic compound.

In an embodiment of the present invention, further hydrophobic compoundsare a combination of at least one natural triglyceride which is solid orliquid at room temperature and a paraffin mixture.

The novel formulations may have a pH of 7 or more. Preferably, they havea pH of from 7 to not more than 10.

The novel formulations can preferably be aqueous formulations having asolids content of up to 50% by weight, based on the total formulation.

The novel formulations have a very good shelf life. Moreover, the novelformulations are excellent for use in the novel process.

The present invention furthermore relates to a process for thepreparation of the novel formulations, also referred to below as novelpreparation process. The novel preparation process can be carried out ingeneral by mixing together the components carboxyl-free polysiloxane,carboxyl-containing polysiloxane and one or more emulsifiers and, ifrequired, a hydrophobic compound or hydrophobic compounds. The sequenceof the addition of the individual components is not critical. This canbe effected, for example, by simple stirring of the components, forexample using a mixer or an Ultra-Turrax stirrer. In some cases, furtherhomogenization is effected, for example by means of a slot homogenizer.Novel formulations having a particularly good shelf life are obtained iffurther homogenization is carried out.

The examples which follow illustrate the invention.

-   1. Preparation of novel formulations 1.1 to 1.4 from    carboxyl-containing polysiloxane, carboxyl-free polysiloxane,    emulsifier and hydrophobic substances

The components mentioned below and shown in table 1 were stirred in abeaker at room temperature.

Carboxyl-containing polysiloxane PS 1: all R¹ are CH₃, A¹ is —(CH₂)₁₀—and Z¹ is a single bond, kinematic viscosity ν 500-850 mm²/s, determinedat room temperature, molecular weight M_(n): 10 000 g/mol, onstatistical average 127 structural elements I and 2 or 3 structuralelements II per molecule, structural elements II are randomlydistributed.

Carboxyl-free polysiloxane PS 2: all R¹ are CH₃, kinematic viscosity ν350 mm²/s, determined at room temperature, molecular weight M_(n): 7 500g/mol.

Emulsifier: N-oleylsarcosine as sodium salt, commercially available fromBASF Aktiengesellschaft.

Natural triglyceride: lipoderm oil, a neatsfoot oil.

Synthetic oil: 36/38 paraffin slack wax, commercially available fromShell and from TotalFina.

The novel formulations 1.1 to 1.4 and, for comparative experiments, theformulations V 1.5 and V 1.6 were prepared. The composition of theformulations is shown in table 1.

For quality control of the emulsions thus obtained, 10 ml were taken andmade up to 100 ml with water. Emulsions having a good shelf life formedovernight. TABLE 1 Component 1.1 1.2 1.3 1.4 V 1.5 V 1.6 PS 1 [g] 5.05.0 5.0 5.0 10.0 — PS 2 [g] 10.0 5.0 5.0 5.0 — 10.0 N-Oleylsarcosine [g]12.9 10.0 10.0 17.0 12.9 10.0 Triglyceride [g] 15.3 15.0 10.0 13.0 12.517.0 NaOH [g] 1.5 1.3 1.2 2.0 1.5 1.5 Paraffin slack wax [g] 15.3 15.018.8 8.0 15.3 13.0 Water [ml] 45.0 51.3 50.0 50.0 50.0 50.0 pH 8.5 8.58.0 9.0 8.5 8.5

EXAMPLE 2 Treatment of Leather EXAMPLE 2.1 Treatment of Leather with theNovel Formulations 1.1

The following general method was employed.

The data in % by weight are based in each case on the shaved weight,unless stated otherwise. In all operations, the barrel was rotated about10 times per minute, unless stated otherwise.

In a rotatable 50 I barrel having internals, 100% by weight of water, 3%by weight of sodium formate and 1% by weight of MgO were added to 2.5 kgof chrome-tanned cattle leather (wet blue) having a shaved thickness of2.5 mm. After 15 minutes, 0.6% by weight of NaHCO₃ was added anddeacidification was effected at 35° C. over a period of 150 minutes sothat a pH of 4.8 resulted.

3% by weight of the following substance having the followingcharacteristic data were then added to the leather:

30% strength by weight aqueous polymer solution partly neutralized withNaOH; homopolymer of methacrylic acid, M_(n) of about 10 000;Fikentscher K value: 12, viscosity of the 30% strength by weightsolution: 65 mPa·s (DIN EN ISO 3219, 23° C.), pH 5.1.

Stirring was carried out for a further 30 minutes.

In the first treatment step, 2% by weight of formulation 1.1 was addedand drumming was carried out for a further 30 minutes. 3% by weight ofthe vegetable tanning agent mimosa extract and 2% by weight of theleather dye Luganil® Black NT, commercially available from BASFAktiengesellschaft, were then added in the course of 10 minutes.Moreover, 2% by weight of the resin tanning agent Relugan® D,commercially available from BASF Aktiengesellschaft, 3% by weight of thevegetable tanning agent Chestnut® and 3% by weight of the syntanBasyntan SL®, commercially available from BASF Aktiengesellschaft, wereadded. The treatment was continued over a period of one hour.

In the second treatment step, a further 7.5% by weight of formulation1.1 were added and drumming was continued at a pH of 4.7 for 12 hours.

100% by weight of water at about 70° C. were then added so that atemperature of 50° C. resulted, and a pH of 3.6 was established byadding formic acid a little at a time over a period of 80 minutes.

The liquor was discharged and the leather was washed with twice 200% byweight of water at 40° C. 100% by weight of water was then added to thetop and the top dye was carried out at 40° C. with a mixture of 0.2% byweight of Leather Black VM and 0.3% by weight of the leather dyeLuganil® Black AS, commercially available from BASF Aktiengesellschaft,and 0.2% by weight of formic acid at a pH of 3.6. Thereafter, the liquorwas discharged, 100% by weight of water was added and treatment waseffected with 3% by weight of chromium(III) sulfate at a pH of 3.5.

Finally, washing was carried out twice with water, drying was effectedand working up was effected in a manner customary in tanning. The novelleather 3.1 was obtained.

The properties of the leathers obtained are shown in table 2.

EXAMPLE 2.2

Example 1 was repeated except that formulation 1.2 was used in each caseinstead of 1.1 in the first and in the second treatment step. The novelleather 3.2 was obtained.

EXAMPLE 2.3

Example 1 was repeated except that formulation 1.3 was used in each caseinstead of 1.1 in the first and in the second treatment step. The novelleather 3.3 was obtained.

EXAMPLE 2.4

Example 1 was repeated except that formulation 1.4 was used in each caseinstead of 1.1 in the first and in the second treatment step. The novelleather 3.4 was obtained.

COMPARATIVE EXAMPLE V 2.5

Example 1 was repeated except that formulation 1.5 was used in each caseinstead of 1.1 in the first and in the second treatment step. Thecomparative leather sample V 3.5 was obtained.

COMPARATIVE EXAMPLE V 2.6

Example 1 was repeated except that formulation 1.6 was used in each caseinstead of 1.1 in the first and in the second treatment step. Thecomparative leather sample V 3.6 was obtained. TABLE 2 Properties of thenovel leathers and of the leathers obtained in the comparativeexperiments Leather or    3.1    3.2    3.3    3.4 V 3.5 V 3.6comparative leather sample Maeser test 18 000 15 000 15 000 15 000 7 600400 26 000 12 000 17 000 18 000 8 700 700 Static water    18    20    19   22   21  27 absorption after 2 hours Dyeing    3    3.5    3.5    5.5   4  4 (shadow) (shadow)The Maeser measurements were carried out using a Maeser tester accordingto ASTM D 2099, in each case as double determinations. The static waterabsorption was carried out at 15% compression and stated in % by weight,based on the finished leather. The dyeing was assessed by visualinspection by a team of testers. The evaluations were effected usingratings: 1 (very good) to 6 (inadequate).4. Preparation of Sulfur-Containing Emulsifiers4.1. Preparation of the Sulfur-Containing E 4.1

115 g (0.3 mol) of the branched alcohol of the formula VIII. 1

were initially taken, in the absence of moisture, in a 1000 mlthree-necked flask equipped with stirrer, internal thermometer andreflux condenser and were heated to 100° C. in an oil bath. 29.4 g (0.3mol) of maleic anhydride were then introduced with stirring, and themixture thus obtainable was stirred for 5 hours at 100° C.

The monoester thus obtainable was cooled to 40° C. and stirred into 210ml of water and partially neutralized by adding 17 g (0.21 mol) of 50%by weight aqueous NaOH, and the mixture obtained was heated to 80° C.Thereafter, 28.5 g of sodium disulfite were added with stirring, and themixture was further stirred over a period of 6 hours at 80° C. Coolingto 40° C. was then effected.

4.2. Preparation of the Sulfur-Containing Emulsifier E 4.2

The procedure was as above but, instead of 115 gof the branched alcoholVIII. 1., 148.9 g (0.3 equivalent, calculated from the OH number) of oxothick oil 135 were used.

-   5. Preparation of Formulation 5.1 According to the Invention using    Carboxyl-Containing Polysiloxane, Carboxyl-Free Polysiloxane,    Sulfur-Containing Sulfur-Containing Emulsifier E 4.1 and Hydrophobic    Substances

The components according to Table 1 which are mentioned below werestirred in a beaker at room temperature using a mixer.

Carboxyl-containing polysiloxane “PS 1”: all R¹═CH₃, A¹: —(CH₂)₁₀—, Z¹:single bond, kinematic viscosity ν in the range 500-850 mm²/s,determined at room temperature, molecular weight M_(n): 10 000 g/mol, onstatistical average 127 structural element I and 2 or 3 structuralelements II per molecule, structural elements II randomly distributed.

Carboxyl-free polysiloxane “PS 2”: all R¹═CH₃, kinematic viscosity ν of350 mm²/s, determined at room temperature, molecular weight M_(n): 7500g/mol.

Emulsifier E 4.1.

Natural triglyceride: lipoderm oil, a neatsfoot oil.

Synthetic oil: slack wax 36/38, commercially available from Shell andfrom Total-Fina.

The mixture thus obtainable was then homogenized with the aid of an SHL105 gap homogenizer from Brau and Luebbe, a pressure of 150 bar and atemperature of 50° C. being chosen.

Formulation 5.1 according to the invention was obtained.

An analogous procedure was adopted for the preparation of formulations5.2 and 5.3 according to the invention and of comparative formulations V5.4 and V 5.5 except that in each case compositions according to Table 3were chosen. The composition of the formulations is shown in Table 3.

For quality control of the emulsions thus obtained, in each case 10 mlwere taken and made to 100 ml with water. Emulsions which werestorage-stable overnight resulted. TABLE 3 Formulation 5.1 5.2 5.3 V 5.4V 5.5 PS 1 [g] 1.0 2.0 0.5 — 4.0 PS 2 [g] 3.0 2.0 3.5 4.0 —Sulfur-containing emulsifier E 4.1 [g] 25 25 25 25 25 Oxo oil 135 [g] 1717 17 17 17 White oil [g] 11.5 11.5 11.5 11.5 11.5 Demineralized water[ml] 42.5 42.5 42.5 42.5 42.5 pH 8.5 8.5 8.5 8.5 8.5

For example 5.6, example 5.1 was repeated, but with 25 g ofsulfur-containing emulsifier E 4.2 instead of E 4.1.

EXAMPLE 6 Treatment of Leather EXAMPLE 6.1 Treatment of Leather withFormulation 5.1 According to the Invention

The following general recipe was followed.

The data in % by weight are based in each case on the shaved weight,unless stated otherwise. In all operations, the barrel was rotated 10times per minute, unless stated otherwise.

In a rotatable 50 I barrel having internals, 100% by weight of water, 3%by weight of sodium formate and 1% by weight of MgO were added to 2.5 kgof chrome-tanned cattle leather (wet blue) having a shaved thickness of2.5 mm. After 15 minutes, 0.6% by weight of NaHCO₃ was added anddeacidification was effected at 35° C. over a period of 150 minutes sothat a pH of 4.8 resulted.

3% by weight of polymer having the following characteristic data werethen added: 30% strength by weight aqueous polymer solution partiallyneutralized with NaOH; homopolymer of methacrylic acid, Mn about 10 000,Fikentscher K value: 12, viscosity of 30% strength by weight solution:65 mPa·s (DIN EN ISO 3219, 23° C.), pH 5.1.

Tanning was carried out for a further 30 minutes.

In the first treatment step, 10% by weight of formulation 5.1 was addedand drumming was carried out for a further 30 minutes. 3% by weight ofthe vegetable tanning agent mimosa extract and 2% by weight of theleather tanning agent Luganil® Black NT, commercially available fromBASF Aktiengesellschaft, were then added in the course of 10 minutes.Moreover, 2% by weight of the resin tanning agent Relugan® D,commercially available from BASF Aktiengesellschaft, 3% by weight of thevegetable tanning agent Chestnut® and 3% by weight of the sulfonetanning agent from EP-B 0 459 168, example K1, were added. The treatmentwas continued over a period of one hour.

In the second treatment step a further 7.5% by weight of formulation 5.1were added and drumming was continued at a pH of 4.7 for 12 hours.

100% by weight of water at about 70° C. were then added so that atemperature of 50° C. resulted, and a pH of 3.6 was established byadding formic acid a little at a time over a period of 80 minutes.

The liquor was discharged and the leather was washed twice with 200% byweight of water at 40° C. 100% by weight of water was then added to thetop and the top dyeing was carried out at 40° C. with a mixture of 0.2%by weight of Leather Black VM and 0.3% by weight of the leather dyeLuganil® Black AS, commercially available from BASF Aktiengesellschaft,and 0.2% by weight of formic acid at a pH of 3.6. Thereafter, the liquorwas discharged, 100% by weight of water was added and treatment waseffected with 3% by weight of chromium(III) sulfate at a pH of 3.5.

Finally, washing was carried out twice with water, drying was effectedand working up was effected in a manner customary in tanning. Theleather 6.1 according to the invention was obtained.

The properties of the leathers obtained are shown in Table 4.

Examples 6.2 and 6.5 and comparative examples V 6.3 and V 6.4

Example 6.1 was repeated, except that formulations 5.2 and 5.3, V 5.4and 5.5 were used in each case instead of 5.1 in the first and in thesecond treatment step. Leathers 6.2 and 6.3 and comparative leathersamples V 6.4 and V 6.5 were obtained. TABLE 4 Properties of theleathers according to the invention and of the comparative leathersamples obtained in the comparative experiments Leather or comparativeleather 6.1 6.2 6.3 V 6.4 V 6.5 sample Formulation used 5.1 5.2 5.3 V5.4 V 5.5 Bally penetrometer, water penetration 120 130 60 40 110  after[min] Static water absorption after 6 hours 29 28 30 34 30 [% by weight]32 29 32 39 28 Dyeing 3 3.5 3  4  5

The Maeser measurements and the water absorption were carried out asabove.

1. A process for imparting water repellency to leather and fur skins,comprising treating the leather or the fur skins with at least oneformulation comprising from 1 to 30% by weight, based on theformulation, of a mixture comprising from 10 to 90% by weight, based onthe mixture, of at least one polysiloxane comprising a carboxyl group,from 90 to 10% by weight, based on the mixture, of at least one carboxylfree polysiloxane, and from 3 to 25% by weight, based on theformulation, of at least one emulsifier.
 2. The process of claim 1,wherein the at least one polysiloxane comprising a carbonyl groupfurther comprises the structural elements of the formulae I and II

wherein R¹ are identical or different and, independently of one another,are hydrogen, a hydroxyl, a C₁-C₄-alkyl, a C₆-C₁₄-aryl, a C₁-C₄-alkoxy,an amino, a mono-C₁-C₄-alkylamino, a di-C₁-C₄-alkylamino or a Z¹-A¹—COOHgroup; A¹ are identical or different and are a linear or a branchedC₅-C₂₅-alkylene; and Z¹ is a direct bond, an oxygen, an amino, acarbonyl, an amido or an ester group.
 3. The process of claim 1, whereinthe at least one formulation comprises from 10 to 70% by weight, basedon the formulation, of at least one further hydrophobic compound.
 4. Theprocess of claim 1, wherein the at least one emulsifier is an N-acylatedamino acid.
 5. The process of claim 1, wherein the at least oneemulsifier comprises sulfur.
 6. The process of claim 5, wherein the atleast one emulsifier comprises at least one compound of the generalformula VI

wherein R⁶ and R⁷ are identical or different and are selected from thegroup consisting of hydrogen, a C₁-C₃₀-alkyl and a C₆-C₁₄-aryl group,and R⁸ is a C₁-C₄-alkyl group or hydrogen.
 7. The process of claim 3,wherein the at least one further hydrophobic compound comprises at leastone natural triglyceride and a paraffin mixture.
 8. The process of claim1, wherein the treating is carried out at a pH of from 4 to
 9. 9. Theprocess of claim 1, wherein the treating is carried out at from 20 to65° C.
 10. A leather produced by the process of claim
 1. 11. A method ofproducing an article of clothing, a piece of furniture, or an automotivepart comprising incorporating the leather of claim 10 into the articleof clothing, the piece of furniture, or the automotive part.
 12. A furskin produced by the method of claim
 1. 13. A formulation comprisingfrom 1 to 20% by weight, based on the formulation, of a mixturecomprising from 10 to 90% by weight, based on the mixture, of at leastone polysiloxane comprising a carboxyl group, from 90 to 10% by weight,based on the mixture, of at least one carboxyl-free polysiloxane, andfrom 3 to 25% by weight, based on the formulation, of at least oneemulsifier.
 14. The formulation of claim 13, wherein the at least onepolysiloxane comprising a carbonyl group further comprises structuralelements of the formulae I and II

wherein R¹ are identical or different and, independently of one another,are hydrogen, a hydroxyl, a C₁-C₄-alkyl, a C₆-C₁₄-aryl, a C₁-C₄-alkoxy,an amino, a mono-C₁-C₄-alkylamino, a di—C₁-C₄-alkylamino or a Z¹-A¹—COOHgroup; A¹ are identical or different and are a linear or a branchedC₅-C₂₅-alkylene; and Z¹ is a direct bond, an oxygen, an amino, acarbonyl, an amido or an ester group.
 15. The formulation of claim 13further comprising from 10 to 70% by weight, based on the formulation,of at least one further hydrophobic compound.
 16. The formulation ofclaim 15 wherein the at least one further hydrophobic compound comprisesat least one natural triglyceride and a paraffin mixture.
 17. A processfor preparing the formulation of claim 13, comprising mixing the atleast one polysiloxane comprising a carboxyl group with the at least onecarboxyl-free polysiloxane and the at least one emulsifier.
 18. Theprocess of claim 1, wherein the at least one polysiloxane comprising acarbonyl group further comprises the structural elements of the formulaeIII a and III b

wherein R¹ are identical or different and, independently of one another,are hydrogen, a hydroxyl, a C₁-C₄-alkyl, a C₆-C₁₄-aryl, a C₁-C₄-alkoxy,an amino, a mono-C₁-C₄-alkylamino, a di-C₁-C₄-alkylamino or a Z¹-A¹—COOHgroup; A¹ are identical or different and are a linear or a branchedC₅-C₂₅-alkylene; and Z¹ is a direct bond, an oxygen, an amino, acarbonyl, an amido or an ester group.
 19. The formulation of claim 13,wherein the at least one polysiloxane comprising a carbonyl groupfurther comprises structural elements of the formulae III a and

wherein R¹ are identical or different and, independently of one another,are hydrogen, a hydroxyl, a C₁-C₄-alkyl, a C₆-C₁₄-aryl, a C₁-C₄-alkoxy,an amino, a mono-C₁-C₄-alkylamino, a di-C₁-C₄-alkylamino or a Z¹-A¹—COOHgroup; A¹ are identical or different and are a linear or a branchedC₅-C₂₅-alkylene; and Z¹ is a direct bond, an oxygen, an amino, acarbonyl, an amido or an ester group.